Phase-locked loops (PLLs) are widely used in, for example, communications for coherent carrier tracking and threshold extension, bit synchronization, as well as symbol synchronization. Phase-locked loop (PLL) is an electronic circuit that controls an oscillator so that it maintains a constant phase relationship relative to an input reference signal. Generally, maintaining a constant phase relationship is otherwise referred to by stating that “the oscillator is in lock with” or “is locked to” the input reference signal.